Performance evaluation of an automotive thermoelectric generator with a non-isometric distributed fin heat exchanger

Abstract

The temperature gradient in the flow direction of automobile exhaust increases the temperature differentiation among thermoelectric modules, which may affect the thermoelectric conversion efficiency and temperature uniformity of a thermoelectric generator. To solve this problem, an innovative optimization method for a heat exchanger with non-isometric distributed fins is proposed. Then, a fluid-thermal-electric multiphysics model is established to evaluate the influence of the distance increment (Δw) on the output performance. The results show that the optimization method can effectively improve the thermoelectric generator's temperature uniformity and output performance, especially when Δw = 0.5. These two performances are increased by 3.61% and 14.48% when the exhaust mass flow is 120 g s⁻¹. In addition, the innovative structure can reduce the backpressure by 0.7% compared to the traditional structure with the same materials. Additionally, the effects of boundary conditions on the output performance are studied and they indicate that the mass flow rate of exhaust has the most significant influence on the output performance enhancement capability, which is inversely proportional to the enhancement of the mass flow rate of exhaust. The structure proposed in this paper offers a guideline for improving the temperature uniformity of a thermoelectric generation system and the structural optimization of a heat exchanger.